The present invention relates to safety seat apparatus for vehicles, especially for passenger motor vehicles, preferably of the type having a passenger restraining belt system for holding a passenger in position in a seat. More particularly, the present invention is related to energy asorption devices which are attached to the seat in such a manner as to absorb collision or deceleration forces acting on the seat, in response to movement of the seat. That is, the energy absorption devices operate to dissipate energy upon movement of one part with respect to the other.
A seat arrangement has been contemplated (DT-OS 1 812 785) in which a backrest portion is pivotal with respect to a seat rest portion under interposition of an energy absorbing element. However, this arrangement has the disadvantage that during the energy absorption, only the backrest portion executes a relative movement in relation to the vehicle body structure. In serious accidents with corresponding high decelerations, the energy absorption related to movement of the backrest portion is often insufficient to protect a person occupying the seat. Further, with this type of arrangement, the backrest itself exhibits a pivotal movement about the point of rotation provided on the attachment thereof with the seat rest portion. That is, since the energy dissipation is only by way of the pivotal movement of the backrest portion, a large pivotal movement thereof is necessary to accommodate dissipation of energy. As a consequence of the extensive movement of the backrest, a highly harmful loading of the human organisms, especially in the head area, takes place during collisions with such apparatus.
The present invention contemplates an improved seat apparatus which avoids the above-mentioned disadvantages. More particularly, the present invention comtemplates constructing seating apparatus in such a way that energy absorption devices operate to dissipate energy in response to movement of the backrest portion as well as to dissipate energy in response to movement of the seat portion, which movements are in relation to the body structure of the vehicle.
In preferred embodiments contemplated by the present invention, a number of separate energy transformers are provided which operationally cooperate with the backrest portion and with the seat portion. Also according to preferred embodiments of the invention, the energy transformers are designed to be effective in two opposite working directions so that collision forces in opposite directions can be adequately absorbed and dissipated.
Also according to preferred embodiments contemplated by the invention, different energy absorption characteristics are provided for the differently positioned energy transformers so as to accommodate a predetermined control of the relative movements of the backrest with respect to the seat rest and the entire seat structure with respect to fixed vehicle support structure.
In one particularly preferred embodiment of the invention, a rotation energy transformer is provided for dissipating energy during pivotal movement of the backrest with respect to the seat rest and a further rotation energy transformer is provided at the connection of the seat rest with the fixed support structure. In addition, this preferred embodiment includes a linear energy transformer interconnected between the fixed support structure and a foot structure which supports the rotation energy transformer of the seat portion. The axis of rotation of the rotation energy transformer interconnecting the foot and the seat rest portion extends essentially midway between the front and rear boundary of the seat rest portion while the axis of rotation of the rotation energy transformer of the backrest extends at a position relative to the seat rest at a level corresponding to the hip joint area of a human passenger occupying the seat. In this connection, it will be understood that the position of this last-mentioned axis of rotation can be determined for an average human body shape for a range of sizes of passengers which are to use the seat. That is, if the seat is to be utilized as a children's seat, the spacing of the axis from the seat portion would understandably be smaller than would be the case for a seat which was to be utilized primarily for adults. The linear energy transformer of the seat rest portion is arranged between the foot and a vehicle floor for accommodating dissipation of energy due to linear sliding of the foot and attached seat with respect to the vehicle floor.
Another preferred embodiment of the invention is constructed as a child's seat which is placed on an existing adult passenger seat. In this embodiment, an energy transformer is provided in the area facing the adult seat, which energy transformer is connected by way of a pull member, such as a cord, wire, or the like, in such a way that relative movement of the parts of the child's seat are dissipated by the energy transformer due to movement of the pull member. In this preferred embodiment, the child's seat is constructed to have a backrest pivotal with respect to the seat rest and with the pull member of the energy transformer connected to the back and seat rest so as to effect a dissipation of energy with a pivotal movement of the backrest and a linear sliding movement of the seat rest along the adult seat. The pull member connected to the energy transformer engages the seat rest by way of a direction reversing device and is fastened to the backrest. A swingable or pivotable support member is provided in the front area of the seat rest for guiding movement of the seat rest along the adult seat.
A primary advantage of the above-mentioned arrangements of the present invention is that, through the construction of the energy absorption devices so as to dissipate energy with movement of both the backrest and the seat portion, sufficient travel for the dissipation of energy is available, even in cases with high decelerations acting on the vehicle. Further, since a plurality of energy transformers are provided, which energy transformers are arranged for dissipating energy by relative movement of different parts with respect to the fixed support structure, these energy transformers can be constructed very simply and reliably. By providing different energy absorption characteristics for the different energy transformers, the energy dissipation and relative movement of the backrest and seat rest can be arranged to minimize passenger injuries with a maximum of total energy dissipation. That is, by appropriately designing the rotation energy transformer at the backrest as having an energy dissipation characteristic which is a percentage or multiple of the energy dissipation characteristic of the rotation energy transformer at the seat rest, an appropriate rotation of both the backrest and seat rest can be obtained which minimizes injuries to the passengers. The provision of both rotation and linear energy transformers is advantageous in that the total space available for the energy absorption is well utilized. The above-mentioned preferred children's seat embodiment is advantageous in that a single energy transformer is required for accommodating both swiveling and linear movement of the parts of the seat. Since the energy transformer in this children's seat embodiment is connectible to the seat by way of a pull member, simple replaceability and exchangeability of the children's seat may be accomplished by merely disconnecting the pull member from the child's seat.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.